Electric arc melting furnace



p 1953 I o. w. SIMMONS ELECTRIC ARC MELTING FURNACE 2 Sheets-Sheet 1Filed July 18, 1950 //VVE/V7'0R Orien W. Simmons y 11%)),- ,SW y; .41

AGENTS.

' 'sept. 15, 1953 Filed July 18, 1950 o. w. SIMMONS ELECTRIC ARCMELTING' FURNACE I 1 him 1 ,T 37 35/ IT- 35 37 /NVE/VTOR.

2 Sheets-Sheet 2 I Oi'ieq W. Simmons By My, ydnwm he AGE/V73.

Patented Sept. 15, 1953 TED PATENT i-orr mesne assignments, to TheBattelle Development Corporation, Columbus, Ohio, at corpora.-

tionioflDelaware Application J my 18, 1950, .Serial No.'174,388

Moreover, the 'number'of electrodeswhich may be used isfrequentlylimited 'by'the' composition of the crucible orthe'geometryfiof the particular crucible. Compositional limitationsarise because the electrodes have to 'be' placedami-nimum distance fromthe wallsofcrucibles formed from certain materials. 'The geometry'of'aparticular crucible alsolim'its thenumber'and/or" the position of the'electrodes Within'the melting chamber. The size of the electrodesthemselves often place a limitation on the total number of electrodeswhich may be. placed within a particularcrucible. Consequently, while itis theoretically possible to direct heat to any desired zone on thesurface of the"-melt"merely by increasing the numberof'electrodes'gquite often this is a practical impossibility.

Additional limitations on the number of electrodes which may be used'areimposed by the necessity, in handling readily reactiblematerialsjofusing an inertatmosphere, the space neededfor 'the'appurtenancesforwhich consequently reduce the 'maximumnumberof electrodes which mayused. Moreover, when readily reactible metals are being melted the typesof materials'from-which' the crucible may be constructed are few innumber and thus an additional limitation is placed upon the maximumnumber of electrodeswhichmay be used.

'This true because certain materials, although suitable for readilyreactiblam'elts, cannotbe subjected to close'contact withele'ctrodes,such as would be the situation'ifa large" numberpf electrodes wereplacedin thecrucible.

It 'is; therefore, one objectof thisinvention to provide an electricarc'melting" furnace which comprisesmeans for varying'the location of theelectric arc" or arcs within the crucible or. furnace without moving theelectrode .or electrodes projecting into the crucible.

It is another object of this invention to provide an electricarcifurnace which comprises means for uniformly=varyingthe position ofasingle-arc or a plurality of ares within said furnace.

"It'is a further object of this invention to provide an electric arcfurnace and means for agitating the molten metal in said furnace.

Various additional objects and advantageous featuresof this inventionwill become apparent to those skilled in the art from the following.description when read in conjunction-with the accompanying drawings, inwhich:

Fig. 1 is a'front elevationperspectiye;view,

partly in section, showing'this inventionapplied to an arc furnacehaving a single, centrally disposed electrode;

Fig. 2 is a plan-view-of the device shown in Fig. 1;

Fig. 3 is a wiring diagram of a'i-dev-ice. usedto control thepositioning of the arcigenerateduin the device shown in Figs 1 and 2;

Fig. 4 is a front elevation perspective miew, partly in section, withportions .broken.-away,-.of.,a modification of this invention appliedto. an electric arc furnace having three electrodes therein; and

Fig. 5 is a view similar to-=Fig. .4: showing a modification of thedevice :shown .therein.

Referring to the drawings,...and more-particularly to Figs. 1 and 2, i0is an .arcwmeltingfurnace crucible or container, which. may .be, made ofa refractory material, or anon-refractory -material, such as copper,suppliedzwithqa,cooling system. Any other material .commonly used forsuch purposes and: which will! withstand heat,

may be used. Where theifurnace is. to, be used to melt' readily reactivematerials, [0. maybe. made of a material whichwill not readily combinewith the active material beingmelted. l!-

is an electrode whichmaybe-madamv anygof the:

various commonelectrode materials,.and if desired, may be-a water-cooledtungsten-,tipp edelectrode, such as is-known-ito thosegskilledin theart. l3 is an electrical lead, contacting-the.- mass of metallicmaterial .I 4 being :formed into an ingot. The electrode II is generallyvthe cathode and the mass of metallic material i5..gen-- erally theanode inthe electricarcf-urnace,

when direct current is used. -"However;:alternating current may also beusedeifectively. Completely enclosing container lib-butspacedrtherefrom, is a ring- 16 ora -magnetic material such as softiron. Attached to'this ringandsequally spaced therearound are inwardlyprojecting pole pieces [8-48. These pole -pieces are .provided'withwindings |:9-'-'-I 9,which are-connected,

as shown in Fig. 3 It is important that ring [6 and pole pieces I8--l8associated therewith be positioned in the horizontal plane which wouldintersect the are formed between electrode H and the molten metal H, inorder to obtain the desired results described hereinafter.

Referring to Fig. 3, the windings |9-l9 on pole pieces l8-l8 areconnected at corresponding ends by resistances -20 and wires 22-22. Arotatable, two contact switch 24, having contacts 25 and 26, is sopositioned that during its rotation it will continuously contactresistances 20-20. Connected to this switch is a source of current 2! inseries with a variable resistance 28. The operation of the device shownin Figs. 1, 2 and 3 is as follows: Assuming that an arc is establishedbetween electrode H and the surface of the metal l4 which is beingformed into an ingot, the pole pieces I8l8 are energized by a suitablesource of current, such as 2! shown in Fig. 3. In the position ofcontacts 25 and 26 shown in Fig. 3 the pole piece having its wind ingsE9 in contact with contact 26 will, let us assume, present a north poleadjacent the container Hi. If that is true, then the remaining two poleswill each be one-half south. Conseuently, the lines of flux will flowfrom the north pole and through the zone inside the container I0 and besplit equally between the south poles and thence back through ring 15 tothe other end of the pole piece having a north pole adjacent containerl0. Since the arc column may be considered a conductor, it will havecircular lines of flux therearound, one portion of which will becancelled out by the lines of flux flowing from the north pole to one ofthe one-half south poles, while the other portion of such lines of fluxwill be added to the magnetic forces flowing from the north pole to theother one-half south pole. Such an unstable group of forces on the arecolumn will cause it to be deflected upwardly away from the anode i4 andin a particular direction depending upon which pole is north and whichpoles are south. The bearing angle, or the direction in which the arccolumn is deflected may be controlled by alternately exciting the polepiece windings. If the pole pieces are regularly alternately excited theelectric arc column will be caused to rotate around the electrode 1 I,while maintaining one end at the electrode. By varying the intensity ofthe voltage supplied to the windings on the pole pieces, the current inturn is varied, which in turn varies the force of the magnetic field,thereby varying the deflection angle or the degree to which the arccolumn is raised from a vertical path between the cathode and the anode.

It is necessary in the three electrode arc furnace to use a device otherthan merely the device shown in Figs. 1 and 2 to control the deflectionof the are, because if the device shown in Figs. 1 and 2 is applied to athree electrode arc furnace the net result is to cause a brush typedischarge which is extremely ineffective as a heating means.

Referring now more particularly to Fig. 4, crucible I0 is shown withelectrical lead 13 and the mass of metallic material l4 therein which isto be formed into an ingot. However, instead of a single electrode, aplurality of electrodes --30 are positioned within the container,equi-spaced from the center thereof and from each other. Surrounding thecontainer i0 is a tubular member 32, preferably made of a non-magneticmaterial such as brass. Wound on this tubular mem- '4 ber 32, is a coil33, attached to a suitable source of electrical energy (not shown).

The operation of this device is as follows:

Arc columns are established between the lower ends of electrodes 30-30and the surface of the metal M which is being formed into an ingot. Thelower ends of such are columns are mutually attracted, and tend toconverge at a point which is on the surface of the metal l4 equi-spacedfrom the electrodes. Electrical energy is then caused to flow throughcoil 33. The resulting vertically extending magnetic field causes thearc column at the lower end of each electrode to be deflected outwardlyfromthe central mutual impingin location and slant upwardly away fromthe anode M. The bearing angle, which is the angle which indicates thedirection in which the arc column is deflected will vary depending uponthe polarity of the coil 33 and the intensity of the magnetic fieldcreated thereby. Therefore, the bearing angle may be controlled bychanging the polarity of the coil and by varying the intensity of themagnetic field created thereby. The intensity of that field will alsoaffect the initial angular deflection of the are columns. The deflectionangle, and to a certain extent the bearing angle, may also be varied bytilting the coil 53 and member 32. If member 32 and the electrodes arenot coaxial, the arc columns will be deflected depending upon thedirection in which the coil is tilted. Their bearing angle will alsovary, but not as noticeably.

Referring now more particularly to Fig. 5, there is shown a crucible It,electrical lead l3 and the mass of metallic material M which is to beformed into an ingot. Electrodes 35-40 are positioned as in Fig. 4.Surrounding crucible I0 is a plurality of vertically extending hollowcylindrical solenoid members 35-35, preferably made of a non-magneticmaterial, and each of which has wound therearound a coil of wire 3l31,each of said coils being connected to a suitable source of electricalenergy. The results obtained with the device shown in Fig. 5 are verysimilar to those obtained with the device shown in Fig. 4, but differ inthat by using the device shown in Fig. 5 it is possible to have certainsections of the ring of members 35-35 create a stronger magnetic fieldthan other sections merely by varying the flux density in individualmembers 3535.

The operation of the device shown in Fig. 5 is as follows:

With an arc column established between the lower end of each of theelectrodes 30-30 and the mass of material It, each of the coil 3l3'| areconnected to sources of electrical energy so that all of the verticallyextending members 35-35 have the same polarity at corresponding ends. Byvarying the flux density in a certain portion of the interior ofcrucible 10, the bearing angle may be more readily controlled thanmerely by changing the entire polarity of the coil and the entiredensity of the magnetic field within the container 10. Moreover, whileboth the deflection and bearing angles may be controlled by tilting theplurality of solenoid members 35-45, these angles may also be controlledby adjusting the polarity of various member 3535, and the flux densityfor those members.

It will be obvious that with all of the devices disclosed herein, theare heat may be directed and concentrated in various parts of the uppersurface of the mass of material being formed into an ingot,. andconsequently an ingot which is homogeneous in character may be formed.

There is an additional and totally unexpected result obtained by the useof the device constituting this invention. If the arc column in a'singleelectrode furnace is rotated in a uniform manner, or if the deflectionangles of the arc columns in a. multiple electrode furnace are suitablyadjusted and the bearing angles for each arc column are established sothat the arc columns are placed in the same relative direction around acircle inscribed through the electrodes, the upper surface of the meltwill be caused to rotate. The reason for this rotation is not known butit is believed to be due to the jet reaction of metallic vapors createdat the point of contact of the arc column with the surface of the melt.Such unexpected rotation of the molten metal insures the formation of anextremely uniform, homogeneous ingot.

While this invention has been described with respect to one electrodeand to three electrode arc furnaces merely for purposes ofsimplification, it is to be understood that this invention should not belimited thereto. The are columns of any number of electrodes may becontrolled and directed with the apparatus disclosed herein.

Furthermore, the magnetic equipment shown in Fig. 1 and Figs. 4 and 5may be combined so that their functions are superimposed, if desired.

While this invention has been described in its preferred embodiment itis to be understood that the words used are words of description ratherthan of limitation and that changes within the purview of the appendedclaims may be made without departing from the true scope and spirit ofthe invention.

What is claimed is:

, 1. An electric arc melting furnace comprising a container means, meansfor producing a vertically-extending electric arc within said containermeans, and means, exterior of said container means, for producing two,divergent, horizontally-extending, magnetic fields which would beadjacent said electric arc, on either side thereof, and within saidcontainer means.

2. An electric arc melting furnace comprising a container means, meansfor producing a verv tically-extending electric are within saidcontainer means, and means, exterior of said container means, forproducing two, divergent, horizontally-extending, magnetic fields ofvariable intensity which would be adjacent said electric arc, on eitherside thereof, and within said container means.

3. An electric arc melting furnace comprising a container means, meansfor producing a vertically-extending electric are within said containermeans, and means, exterior of said container means, for producing two,divergent, horizontally-extending, movable, magnetic fields which wouldbe adjacent said electric arc, on either side thereof, and within saidcontainer means.

4. An electric arc melting furnace comprising a container means, meansfor producing a vertically-extending electric are within said containermeans, and three, equi-spaced, radially extending, horizontallypositioned, solenoid members, exterior of said container means, andlying in a plane extending through the zone which would be occupied byan electric arc produced by said means for producing said electric arefor producing two, divergent, horizontally extending, magnetic fieldswhich would be adjacent said electric arc, on either side thereof, andwithin said container means.

5. An electric arc melting furnace comprising a container means, meansfor producing a vertically-extending electric are within said containermeans,'an annular magnetic material containing member, exterior of saidcontainer means and. equi-spaced therefrom, but lying in a planeextending through the zone which would be occupied by an electric areproduced by said means for producing an electric arc, and threeequispaced, radially-extending, horizontally positioned, solenoidmembers inwardly-extending from said annular member for producing two,divergent, horizontally extending, magnetic fields which would beadjacent said electric arc, on either side thereof, and within saidcontainer means.

6. An electric arc melting furnace comprising a container means, asingle vertical electrode adapted to produce an electric arc within saidcontainer means, an annular magnetic material containing member,exterior of said container means and equi-spaced therefrom, but lying ina plane adjacent the lower end of said electrode, and three,equi-spaced, horizontally positioned, radially-extending solenoidmembers, inwardlyextending from said annular members for producing two,divergent, horizontally extending, magnetic fields which would beadjacent said electric arc, on either side thereof, and within saidcontainer means.

ORIEN W. SIMMONS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 586,822 Patten July 20, 1897 1,094,354 Von Wilmowsky Apr. 21,1914 1,094,381 Von Wilmowsky Apr. 21, 1914 1,346,223 Lombardi July 13,1920 1,404,734 Bennett Jan. 31, 1922 1,496,299 Clifford June 3, 19242,046,117 Guest June 30, 1936 2,198,304 Cornelius Apr. 23, 19402,256,518 Dreyfus Sept. 23, 1941 2,363,582 Gerber et a1. Nov. 28, 19442,513,082 Dreyfus June 27, 1950

